According to eussNL of the Dev Wiki they aren't 'Debug' Firmware PUPs like most are familiar with in the PS3 scene, and there is no 'DEX' naming at all with PS4 development hardware/software.

Here's to hoping one day Sony's PlayStation 4 follows suit of being able to run PS4 game backups similar to the PS3 and PS Vita consoles, and if anyone has more PS4 DevKit / TestKit Firmware PUPs remember sharing is caring!

Following their previous revision, Sony has now released a PlayStation 4 System Software / PS4 Firmware 4.07 Update which once again improves the quality of the system performance (aka patches exploit security holes).

My cable guy was just looking for a discounted PlayStation 4 bundle for the holidays, and it appears Sony has answered dropping the Uncharted 4 PS4 bundle to $249.99 from December 11 to the 24th, 2016.